Method and Apparatus for Use in the Production of a Surgical Guide

ABSTRACT

A method of producing a modification plan for producing a surgical guide from an impression element includes: obtaining surface data representing a configuration of a surface of an impression element providing an impression of a surgical site; obtaining image data of a patient&#39;s anatomy; obtaining surgical plan data providing a surgical plan with respect to features in the image data representing anatomical features of the patient&#39;s anatomy; registering the impression element using the surface data and the image data with anatomical features of the patient&#39;s anatomy; and producing a modification plan from the surgical plan data using the registration of the impression element with anatomical features of the patient&#39;s anatomy, the modification plan being a plan for modifying the impression element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/GB2014/053304 having a filing date of Nov. 5, 2014, entitled “Methodand Apparatus for Use in the Production of a Surgical Guide”, which isrelated to and claims priority benefits from U.K. patent application No.1320745.1 filed on Nov. 25, 2013, also entitled “Method and Apparatusfor Use in the Production of a Surgical Guide”. The '304 internationalapplication and '745.1 U.K. application are hereby incorporated byreference herein in their entireties.

FIELD OF THE INVENTION

The present disclosure relates to a method and apparatus for use in theproduction of a surgical guide, for example in the intraoperativeproduction of a surgical guide.

BACKGROUND OF THE INVENTION

Accurate placement is important to the success of many surgical implantsand prostheses. Guidance devices for use in surgery have been developedto aid in placement. These systems often take the form of large andbulky robotic guides or navigation systems that can be registered to thepatient's anatomy and the pre-operative imaging data. These systems arecostly, significantly interrupt the surgeons work flow, requireextensive set-up time, extra trained staff and are inconvenient tooperate in the limited space of the modern operating theatre. Thesesystems also require lengthy cleaning procedures and are oftencomplicated to set up with the added risk that their digital naturemakes them susceptible to errors while guiding the procedure.

Rapid manufacturing/prototyping techniques have been used effectively toproduce simple bespoke guides that can be sterilized and brought intothe surgical field. Such patient specific instrumentation is used inmany surgical specialties such as dentistry, maxillofacial surgery andorthopedics. These guides have been shown to be useful in many differentprocedures as their bespoke nature allows them to be created to fitspecifically onto a particular piece of anatomy in a similar manner to ajigsaw piece fitting a specific location. These guides, can, forexample, be produced with holes or cutting slots to facilitate theguidance of surgical tools such as a drill during the procedure.

Previously, guides produced by rapid manufacturing/prototypingtechniques have been time consuming to produce with long manufacturingtimes and logistics chains, often needing post production processing.Commercial 3D printing equipment is expensive and each printed guide hadto be individually sterilized. The guides had to be produced in advanceof the surgery and thus were unable to be modified once the operationhad commenced if they were found to be problematic or the parameters ofthe operation were changed.

What is needed is an improved method and apparatus for use in theproduction of surgical guides.

SUMMARY OF INVENTION

A method of producing a modification plan for producing a surgical guidefrom an impression element can include:

obtaining surface data representing a configuration of a surface of animpression element providing an impression of a surgical site;

obtaining image data of a patient's anatomy;

obtaining surgical plan data providing a surgical plan with respect tofeatures in the image data representing anatomical features of thepatient's anatomy;

registering the impression element using the surface data and the imagedata with anatomical features of the patient's anatomy;

producing a modification plan from the surgical plan data using theregistration of the impression element with anatomical features of thepatient's anatomy, the modification plan being a plan for modifying theimpression element.

In some embodiments, the modification plan is in accordance with thesurgical plan data, that is to say that the modification plan is derivedfrom the surgical plan data to enable a guide produced with themodification plan to guide surgery in accordance with the surgical plan.

In some embodiments, the surgical site can be an operatively exposedsurgical site.

The modification plan is a plan of how to modify the impression elementto produce a surgical guide. In some embodiments, the modification planis a structural modification plan of how to structurally modify theimpression element. In some embodiments, the modification plan is atooling plan, a tooling plan being a plan of how to tool the impressionelement. In other embodiments, the modification plan is a plan of how tomark the impression element for example with guiding marks forsubsequent cutting by hand. Tooling can include cutting or other methodsof creating an opening, such as a gap or a hole, in the impressionelement, such as by cutting, drilling, milling, etc.

In some embodiments, the image data of the patient's anatomy includesimage data of anatomical features in the vicinity of the surgical site.Generally, the image data is captured before the surgical site isexposed and therefore does not include image data directly relating tothe exposure of the surgical site. The image data generally does notinclude the entirety of the patient's anatomy.

In some embodiments, the surgical plan is an electronic plan made, withreference to features of the image data which represent anatomicalfeatures of the patient's anatomy, defining how surgical interventionsare to be made.

Registering two elements together includes calibrating how the featuresof one relate to the features of the other, for example by determiningthe configuration of both elements within a common coordinate system orframe of reference. For physical elements this is in general done bycorrelating data representing each element. Registration can beconsidered to provide a relative position.

In some embodiments, the impression element is registered directly withanatomical features, meaning it is not necessary for a reference markerto be inserted before the image data is captured.

In some embodiments, registering the impression element using thesurface data and the image data with anatomical features of thepatient's anatomy includes identifying, for a plurality of points on thesurface of the impression element, a corresponding plurality of pointson anatomical features of the patient, wherein a corresponding pluralityof points on anatomical features of the patient are the plurality ofpoints of the surgical site adjacent to the plurality of points on theimpression element when the impression element is in place at thesurgical site.

In some embodiments, registering the impression element using thesurface data and the image data with anatomical features of thepatient's anatomy includes registering the surface data with features inthe image data which represent anatomical features of the patient'sanatomy.

In some embodiments, registering the impression element using thesurface data and the image data with anatomical features of thepatient's anatomy includes identifying, for a plurality of points in thesurface data representing points on the surface of the impressionelement, a plurality of points in the image data which representcorresponding points on anatomical features of the patient.

In some embodiments, a registration of an impression element withanother object can include a determination of a relative position of aplurality of points on the surface of the impression element withrespect to the other object.

In some embodiments, the impression element is a molded element,preferably molded by being placed against the surgical site.

In some embodiments, the modification plan includes instructions foroperating a production apparatus to modify or to guide modification ofthe impression element.

In some embodiments, the instructions can be for presentation to a userto allow the user to operate the production apparatus.

In some embodiments, producing the modification plan includes producinga plan defined with respect to features of the surface data,representing features of the impression element. In other words, in suchembodiments, the surgical plan defined with respect to features of theimage data is converted to a plan defined with respect to features ofthe surface data using the registration of the surface data withfeatures in the image data. This plan can be used to produce theinstructions.

The instructions can be modification instructions, or they can beinstructions to position a modification guide to guide an externalmodification tool.

In some embodiments, the method includes registering the impressionelement with the production apparatus using the surface data, theproduction apparatus including a modification tool for modifying theimpression element or a modification guide for guiding a modificationtool; wherein producing instructions includes producing instructionsbased on a calibrated position of the modification tool or modificationguide and the registration of the impression element with the productionapparatus.

In some embodiments, by registering the impression element with theproduction apparatus, the position of the impression element withrespect to the production apparatus, for example in a receptor assembly,is calibrated. Therefore, desired modifications defined with respect tothe impression element can be converted into modifications defined withrespect to the production apparatus. By having the position of themodification tool or modification guide of the production apparatuscalibrated, these modifications defined with respect to the productionapparatus can be converted into instructions for the productionapparatus, for example operation instructions defining how to operatethe modification tool to make the desired modifications to theimpression element, or instructions defining how to position themodification guide to enable such desired modifications to be made.

In some embodiments, registering the impression element with theproduction apparatus includes registering the surface data with datarepresenting a structure of the production apparatus. Producinginstructions can include converting a plan defined with respect tofeatures of the surface data into a plan defined with respect to datarepresenting a structure of the production apparatus by using theregistration of the surface data with data representing a structure ofthe production apparatus. Using the calibration of the position of themodification tool or modification guide, this can be converted intoinstructions for use of the modification tool or modification guide,such as operation instructions governing the operation of themodification tool or modification guide.

In some embodiments, registering the impression element with theproduction apparatus uses data representing a relative position of asurface configuration recorder with respect to the production apparatus.In other embodiments, this registration can use a predetermined relativeposition with respect to the production apparatus of a feature in thesurface data, for example surface data representing a reference elementof a carrier.

The instructions can include instructions concerning how to move theimpression element and/or modification guide and/or how to operate themodification tool.

The instructions provide how to modify the impression element, or how toguide modification of the impression element, to produce a guide toguide surgery according to the surgical plan.

In some embodiments, the method includes registering the impressionelement with a carrier carrying the impression element using the surfacedata.

In some embodiments, registering the impression element with a carrierincludes using a calibration of a position of the carrier during therecording of the surface data for example with respect to the productionapparatus. In some embodiments, the production apparatus can include areceptor assembly configured to hold the carrier in a predeterminedrelative position during the recording of the surface data and duringmodification of the impression element. In other embodiments, thesurface data can include data representing a reference element of thecarrier.

The carrier can have a predetermined configuration.

In some embodiments, registering the impression element with a carrierincludes registering the surface data with data representing a structureor configuration of the carrier.

In some embodiments, obtaining surface data includes operating a scannerto scan the surface of the impression element. In other embodiments, thesurface data can be obtained by touching a digitizer arm against aplurality of points on the surface of the impression element.

Where the surface data is obtained from a scanner, the surface data caninclude data representing distance from the scanner to a plurality ofpoints on the on the surface of the impression element.

Preferably, the scanner is an optical scanner since this is a preciseway of scanning, and offers greater precision than CT scans.

A method of producing a surgical guide can include:

producing a modification plan as above, wherein obtaining surface dataincludes operating a surface configuration recorder to obtain thesurface data; and

modifying the impression element in accordance with the modificationplan.

Preferably, the surface configuration recorder is a scanner.

Preferably, modifying the impression element in accordance with themodification plan includes operating a production apparatus to modifythe impression element, or to guide modification of the impressionelement, in accordance with the modification plan to produce thesurgical guide.

In some embodiments, operating the production apparatus is in accordancewith the instructions discussed above.

Preferably, operating the production apparatus includes operating amodification tool of the production apparatus, operating a modificationtool preferably including one or more of cutting, drilling and milling.

In other embodiments, operating the production apparatus can includeoperating a modification guide.

The method preferably includes placing a moldable element against thesurgical site to form the impression element.

A moldable element for use in surgery can include:

moldable material for being placed against a surgical site to form animpression of that site; and

a reference element coupled to the moldable material for allowing aconfiguration of a surface of the moldable material to be recorded withrespect to a known point of reference.

The moldable element preferably includes a carrier for carrying themoldable material, the carrier including the reference element.

The reference element preferably includes a coupling element forcoupling the carrier to a production apparatus in a predeterminedposition.

The carrier can include an identification element, the identificationelement optionally identifying a particular patient or a particularsurgical procedure with which the moldable element is to be used.

In some embodiments, the carrier includes a body and at least oneregistration arm extending from the body, the at least one registrationarm being fixed with respect to the body, the at least one registrationarm being operable to register contact with bone whereby to assistregistration of the moldable element with anatomical features of apatient by providing information relating to a position of bone withrespect to the body of the carrier when the carrier is in place at asurgical site.

In some embodiments, the carrier includes a coupling element forcoupling to a guiding element for guiding a surgical component tointeract with a surgical site.

In some embodiments, the carrier includes a guiding element for guidinga surgical component to interact with a surgical site.

In some embodiments, the carrier includes a body and the guiding elementis provided on an arm extending from the body.

In some embodiments, the guiding element is fixed with respect to thebody.

The guiding element is preferably selectively configurable.

In some embodiments, the guiding element can be selectively configuredinto a plurality of different configurations, for example the guidingelement can be or can include a component which can be aligned in aplurality of orientations, and/or positioned in a plurality ofpositions.

Preferably, the guiding element includes a surgical tool for beingguided by the respective guiding element.

In some embodiments, the guiding element includes a screw guide forguiding a screw to be screwed into a surgical site, the screw guideenabling registration of a screw screwed into a surgical site withanatomical features of a patient.

In some embodiments, the moldable material includes a first surfacedesigned to receive an impression of a surgical site and to be scanned,and wherein the reference element includes a projection projectinglaterally beyond a side of the first surface whereby to be included in ascan of the first surface.

In some embodiments, the reference element can include one or more armsextending from the carrier. Having both the first surface and thereference element recorded means that the configuration of the firstsurface can be determined with respect to the reference element.

In some embodiments, the moldable material includes an outer layer ofthermoplastic material and an inner layer of permanently deformablematerial.

The thermoplastic material preferably has a transition temperature belowa tissue damaging threshold.

A surgical guide or jig can include a moldable element as above havingbeen molded to form an impression of a surgical site to provide a tissuefitting surface, and modified, preferably cut, drilled, or prepared, toprovide a guide for a surgical tool.

An impression element holder can include:

a first coupling element for coupling the holder into a productionapparatus in a predetermined position;

a second coupling element for coupling an impression element into theholder in a predetermined position;

a receiving zone for receiving an impression element coupled to thesecond coupling element without contact with a production apparatuscoupled to the first coupling element.

The impression element holder preferably includes an open side to allowan impression element held within the holder to be optically scanned.

A production apparatus for the production of a surgical guide caninclude:

a receptor assembly having received therein an impression elementconforming to a shape of a surgical site; and

a modification tool for modifying the impression element or amodification guide for guiding a modification tool; wherein themodification tool or modification guide and the impression element arepositionable in a plurality of predetermined relative positions to allowthe impression element to be modified in accordance with a modificationplan, wherein a modification plan is a plan for modifying the impressionelement and is derived from a surgical plan and a registration of theimpression element with anatomical features of a patient's anatomy.

A production apparatus for the production of a surgical guide caninclude:

a receptor assembly for receiving an impression element conforming to ashape of a surgical site;

a surface configuration recorder for recording a configuration of asurface of an impression element received by the receptor assembly toproduce surface data for registering that impression element withanatomical features of a patient's anatomy and with the productionapparatus; and

a modification tool for modifying an impression element received by thereceptor assembly or a modification guide for guiding a modificationtool; wherein the modification tool or modification guide and animpression element received by the receptor assembly are positionable ina plurality of predetermined relative positions to allow an impressionelement received by the receptor assembly to be modified in accordancewith a modification plan, wherein a modification plan is a plan formodifying an impression element and is derived from a surgical plan anda registration of that impression element with anatomical features of arespective patient's anatomy.

Preferably, the surface configuration recorder is a scanner, preferablyan optical scanner.

Preferably, the modification tool includes one or more of a cutter forcutting an impression element, a drill for drilling an impressionelement, a milling component for milling an impression element, a slotsaw for sawing, and a marker for marking an impression element.

The apparatus preferably includes:

a processor for determining, from a modification plan and a registrationof the apparatus with an impression element received by the receptorassembly, a desired relative position of the modification tool ormodification guide with respect to that impression element to enablethat impression element to be modified in accordance with thatmodification plan.

In some embodiments, the processor is operable to obtain a modificationplan from an external computing device.

In some embodiments, the processor is operable to obtain patientregistration data providing a registration of an impression elementreceived by the receptor assembly with anatomical features of arespective patient's anatomy, wherein the processor is operable toobtain a surgical plan, and wherein the processor is operable tocalculate a modification plan from the patient registration data and thesurgical plan.

In some embodiments, a registration of an impression element withanatomical features of a patient's anatomy includes a registration ofsurface data representing a configuration of a surface of thatimpression element with features of image data representing anatomicalfeatures of a patient's anatomy. This can include an identification, fora plurality of points in the surface data representing points on thesurface of the impression element, with a plurality of points in theimage data which represent corresponding points on anatomical featuresof the patient.

Preferably, the processor is operable to determine how to modify animpression element in accordance with the surgical plan by using thepatient registration data to determine how a respective impressionelement will align with a surgical site, and thereby determining how tomodify an impression element in order to provide a configuration at asurgical site that is in accordance with the surgical plan.

Preferably, the processor is operable to determine patient registrationdata from image data of a patient's anatomy and surface data from thesurface configuration recorder.

In some embodiments, the processor is operable to register an impressionelement received in the receptor assembly with the production apparatus,preferably with the receptor assembly, using surface data from thesurface configuration recorder.

The processor can be calibrated with a relative position of the surfaceconfiguration recorder, and the modification tool or modification guide.

The processor can be operable to adapt its calibration in response tomovement of the surface configuration recorder and/or modification tooland/or modification guide.

The apparatus can include a control unit operable to adjust a relativeposition of the modification tool or modification guide with respect toan impression element received by the receptor assembly in order toplace them in a desired relative position.

The relative position of the modification tool or modification guidewith respect to an impression element received by the receptor assemblycan be adjusted by adjusting the relative position of the modificationtool or modification guide with respect to the receptor assembly, whichcan include adjusting the position of the modification tool ormodification guide and/or the receptor assembly.

The control unit can include the processor. The processor and/or controlunit can be configured to perform the method above.

In some embodiments, the control unit is operable to adjust a positionof the receptor assembly and/or the modification tool or modificationguide to enable modification in accordance with a modification plan.

In some embodiments, the control unit is operable to control themodification tool to modify an impression element received by thereceptor assembly in accordance with a respective modification plan.

In some embodiments, the control unit is calibrated with relativepositions of the surface configuration recorder and of the modificationtool or modification guide and optionally of the receptor assembly.

In some embodiments, the control unit is operable to adapt itscalibration in response to movement of the surface configurationrecorder and/or receptor assembly and/or modification tool and/ormodification guide.

Preferably, the control unit is operable to obtain spatial registrationdata providing a registration of an impression element received by thereceptor assembly with the apparatus, and wherein the control unit isoperable to control the modification tool to modify a receivedimpression element in accordance with a modification plan using thespatial registration data.

Preferably, the receptor assembly includes a coupling or attachmentelement to cooperate with a corresponding coupling or attachment elementon an impression element.

Preferably, the receptor assembly is configured to receive an impressionelement holder for holding an impression element without contact withthe apparatus to prevent, or at least reduce, contamination of areceived impression element or the apparatus.

In some embodiments, the modification tool can releasably hold a toolelement to enable a used tool element to be substituted for a newsterile tool element.

The tool element can for example be a cutting element for a cutter, adrill bit for a drill, a milling component head for a milling component,a marker element for a marker, or a saw element for a saw.

The apparatus can include a motor for moving the modification tool ormodification guide.

The apparatus can include a motor for moving the receptor assembly.

A method can include:

obtaining from a surface configuration recorder surface datarepresenting a configuration of a surface of an impression elementproviding an impression of a surgical site;

obtaining data relating to a relative position of a location for theguiding element with respect to the surface;

obtaining image data of a patient's anatomy;

registering the impression element with the location for the guidingelement using the surface data and the data relating to the relativeposition of the location for the guiding element with respect to thesurface;

registering the impression element using the surface data and the imagedata with anatomical features of the patient's anatomy;

registering the guiding element with anatomical features of thepatient's anatomy using the registration of the impression element withanatomical features of the patient's anatomy and the registration of theimpression element with the location for the guiding element.

The guiding element can be at the location for the guiding elementduring recordal, or the guiding element can have been removed beforerecordal of the surface data.

The data relating to a relative position of the location for the guidingelement with respect to the surface can include data relating to arelative position of the location for the guiding element with respectto the surface configuration recorder.

The data relating to a relative position of the location for the guidingelement with respect to the surface can include data identifyingfeatures in the surface data representing the location of the guidingelement or it can include data identifying features in the surface datarepresenting a reference marker and data providing a relative positionof the location for the guiding element with respect to the referencemarker. In other words, obtaining data relating to a relative positionof the location for the guiding element with respect to the surface caninclude determining from the surface data a relative position of areference marker and/or the location of the guiding element with respectto the surface.

In some embodiments, the data relating to a relative position of thelocation for the guiding element with respect to the surface includesdata relating to a relative position, during the recordal of the surfacedata, of the surface and a carrier carrying the impression element,wherein the carrier includes or can receive the guiding element; andwherein registering the impression element with the guiding elementincludes registering the impression element with the carrier using thesurface data and the data relating to the relative position of thesurface and the carrier.

In some embodiments, obtaining data relating to a relative position ofthe surface and the carrier includes determining from the surface data arelative position of a reference element of the carrier with respect tothe surface.

In some embodiments, the guiding element is configurable, and the methodincludes:

obtaining surgical plan data providing a surgical plan with respect tofeatures in the image data representing anatomical features of thepatient's anatomy;

determining a configuration for the guiding element from the surgicalplan data using the registration of the location for the guiding elementwith anatomical features of the patient's anatomy.

In some embodiments, registering the guiding element with anatomicalfeatures of the patient's anatomy includes registering data relating toeach of the plurality of configurations of the guiding element withfeatures in the image data representing anatomical features.

The method can include configuring the guiding element in accordancewith the determined configuration.

The method can include guiding the surgical component using the guidingelement to perform a surgical interaction with the patient.

A method of registering a guiding element with a patient's anatomy caninclude:

obtaining from a surface configuration recorder surface datarepresenting a configuration of a surface of an impression elementproviding an impression of a surgical site;

obtaining data relating to a relative position during the recordal ofthe surface data of the surface configuration recorder and a carriercarrying the impression element, wherein the carrier includes or canreceive a guiding element for guiding a surgical component;

obtaining image data of a patient's anatomy;

registering the impression element with the carrier using the surfacedata and the data relating to the relative position of the surfaceconfiguration recorder and the carrier;

registering the impression element using the surface data and the imagedata with anatomical features of the patient's anatomy;

registering the guiding element with anatomical features of thepatient's anatomy using the registration of the impression element withanatomical features of the patient's anatomy and the registration of theimpression element with the carrier.

In some embodiments, registering the impression element with the carrierincludes registering the surface data with data relating to a structureor configuration of the carrier.

In some embodiments, registering the guiding element with anatomicalfeatures of the patient's anatomy uses data relating to a position ofthe guiding element, for example with respect to the carrier.

In some embodiments, registering the guiding element with anatomicalfeatures of the patient's anatomy includes registering data relating toa structure of the guiding element with features of the image datarepresenting anatomical features.

Preferably, the guiding element is configurable, and the methodincludes:

obtaining surgical plan data providing a surgical plan with respect tofeatures in the image data representing anatomical features of thepatient's anatomy;

determining a configuration for the guiding element from the surgicalplan data using the registration of the impression element withanatomical features of the patient's anatomy.

In some embodiments, registering the guiding element with anatomicalfeatures of the patient's anatomy uses data relating to a position withrespect to the carrier when the guiding element is coupled to thecarrier of those parts of the guiding element that are fixed withrespect to the carrier when the guiding element is coupled to thecarrier.

In other embodiments, registering the guiding element with anatomicalfeatures of the patient's anatomy uses data relating to each of theplurality of configurations of the guiding element with respect to thecarrier when the guiding element is coupled to the carrier.

The method can include configuring the guiding element in accordancewith the determined configuration.

In some embodiments, the configuration for the guiding element isdetermined in accordance with the surgical plan data, that is to saythat the configuration is derived from the surgical plan data to enablethe guiding element to guide surgery in accordance with the surgicalplan.

In some embodiments, the surgical component can be a surgical tool andthe guiding element can include the surgical tool that the guidingelement is configured to guide to enable surgery to be carried out inaccordance with the surgical plan.

In some embodiments, obtaining data relating to a relative positionduring the recordal of the surface data of the surface configurationrecorder and the carrier includes determining from the surface data arelative position of a reference element of the carrier with respect tothe surface or surface configuration recorder.

In some embodiments, the reference element has a known position withrespect to the carrier as a whole, and the position of the carrier withrespect to the surface or surface configuration recorder can thereby bedetermined.

The method can include guiding the surgical component using the guidingelement to perform a surgical interaction with the patient.

In some embodiments, a surgical screw or other marker can be attached tothe patient's anatomy using the guiding element, and that marker can beregistered to anatomical features of the patient's anatomy, therebyenabling that marker to be used as a reference point for surgicalnavigation or guidance.

A registration apparatus for use in the registration of a guidingelement with a patient's anatomy can include:

a receptor assembly including a coupling element for coupling to acoupling element on a carrier for an impression element whereby to holda carrier for an impression element in a predetermined position; and

a surface configuration recorder for recording a configuration on asurface of an impression element carried by a carrier received by thereceptor assembly to produce surface data for registering thatimpression element with anatomical features of a patient's anatomy andwith that carrier and thereby for registering that carrier withanatomical features of a patient's anatomy.

A kit for producing a surgical guide can include:

an apparatus as above; and

at least one impression element being a moldable element as above.

In other embodiments, a kit for producing a surgical guide can included:

an apparatus as above; and

moldable material for placing against a surgical site to form animpression element.

The kit preferably includes at least one carrier for being attached tothe or a part of the moldable material to carry the moldable material.

In some embodiment a computer program can perform the method(s)described above when executed on a computing device.

A programmable guiding element for guiding a surgical intervention caninclude:

a coupling element for coupling the guiding element to a carrier for animpression element; and

a tool guide selectively configurable in a plurality of configurationsfor guiding a tool to make a surgical intervention, wherein each of theplurality of configurations provides the tool guide in a differentpredetermined position with respect to the coupling element.

The guiding element can include a surgical tool to be guided by the toolguide.

A method can include:

obtaining surface data representing a configuration of a surface of animpression element providing an impression of a surgical site;

obtaining image data of a patient's anatomy; and

registering the impression element using the surface data and the imagedata with anatomical features of the patient's anatomy.

In some embodiments, the carrier can be used to temporarily attach theimpression element to other surgical tools such that the impressionelement can be molded to surgical anatomy in difficult to reach placesfor example.

In some embodiments, a moldable material can be placed in a surgicalsite in order to form an impression of that site. The material can thenbe placed in an apparatus which can scan the impressed surface of themoldable material. The apparatus is calibrated so that it can spatiallyregister the scan with the apparatus. For example, the moldable materialcan be attached to a carrier component and the material can be placed inthe apparatus by connecting an attachment element on the carriercomponent to a corresponding element in the apparatus so that thematerial is in a pre-calibrated location within the apparatus. Thescanner can also be in a predetermined calibrated position within theapparatus enabling a determination from the scan of the position of thematerial with respect to carrier component and hence with respect to therest of the apparatus. Using the fact that the material is known to fitagainst a surgical site, the scanned material can be spatiallyregistered with image data of the patient. A surgical plan whichdictates how surgery at the surgical site should proceed can then beconverted into a plan as to how to modify, for example cut, the materialto form a guide to guide the surgery. The apparatus can either serve asa marker to mark or guide modification, for example cutting, of thematerial, or it can itself modify the material in accordance with themodification plan. The modified material, when placed back into thesurgical site, can thus act as a surgical guide.

It is to be appreciated that certain embodiments can be incorporated ascode (e.g., a software algorithm or program) residing in firmware and/oron computer useable medium having control logic for enabling executionon a computer system having a computer processor. Such a computer systemtypically includes memory storage configured to provide output fromexecution of the code which configures a processor in accordance withthe execution. The code can be arranged as firmware or software, and canbe organized as a set of modules such as discrete code modules, functioncalls, procedure calls or objects in an object-oriented programmingenvironment. If implemented using modules, the code can comprise asingle module or a plurality of modules that operate in cooperation withone another.

In some embodiments, guides produced via the methods and apparatusesdisclosed her can be produced intraoperatively directly from animpression of the surgical site, thereby minimizing manufacturing timeand logistics chains, removing the expense of 3D printing equipment, andenabling custom guides to be manufactured or modified during surgery inaccordance with the desired procedure.

Preferred embodiments use a surgical navigation registration techniqueand associated apparatus for the intraoperative manufacture of a bespokeguide to facilitate the placement, operation or use, of a surgical tool,implant or accessory.

Some embodiments can provide a cost effective system capable ofproducing patient specific surgical guides with minimal production time.Bespoke guides can be produced intraoperatively without extended set uptime, cleaning or interruption to the surgical workflow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a planned placement for a guide wire in ascapula.

FIGS. 2A and 2B are, respectively, a perspective and side view of aguide blank.

FIG. 3 is a perspective view of a production apparatus.

FIG. 4 is a perspective view of a receptor assembly and modificationtool for the production of the production apparatus shown in FIG. 3;

FIG. 5 is an exploded view showing the insertion of the guide blank ofFIG. 2 into the production apparatus of FIG. 3;

FIG. 6 is a diagrammatic flow chart showing the use of the guide blankof FIG. 2 to take an impression of a surgical site;

FIG. 7 is a side view showing a guide made from the guide blank of FIG.2;

FIG. 8 shows a guide blank according to another embodiment being placedagainst a surgical site;

FIG. 9A shows a guide blank.

FIG. 9B shows the guide blank of FIG. 9A subject to a deforming force;

FIG. 10 shows the production of a guide blank according to anotherembodiment.

FIG. 11 shows a surgical plan being constructed;

FIG. 12 shows a guide blank holder and a carrier.

FIG. 13 shows a production apparatus.

FIG. 14 shows an internal view of the production apparatus of FIG. 13;

FIG. 15 shows the carrier of FIG. 12 with a moldable element in place ona model of a scapula;

FIG. 16 shows the guide blank holder and carrier of FIG. 12 in thereceptor assembly of the production apparatus of FIGS. 13 to 15;

FIG. 17 shows another view of the arrangement of FIG. 16;

FIG. 18 shows a carrier.

FIG. 19 shows a guiding element.

FIG. 20 shows a guiding element.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT(S)

The above drawings are schematic only and not to scale. Embodiments aredescribed within the framework of the total shoulder arthroplastyprocedure, with specific focus on a method for orientating the glenoidcomponent of the prosthesis within the glenoid cavity of scapula 10 asshown in FIG. 1. However, some embodiments can also be used for othersurgical procedures, for example for different parts of the human bodyincluding dental surgery, or for the body of a different animal, and/orwith different guiding structures.

As commonly practiced in many surgical fields; once preoperative imagingdata such as an MRI or CT scan has been obtained, a surgeon canpre-operatively digitally plan the procedure to be performed usingsoftware planning tools. Such software can produce a prescription forthe procedure. For the purposes of this description, it is assumed thatsuch a prescription in the form of a suitable digital plan (DP) definesthe placement of guide wire 12 into the glenoid cavity of scapula 10.

In other embodiments, a digital plan can define various other surgicalinterventions to be made. The digital plan defines a surgical procedurewith respect to features in the pre-operative imaging data representinganatomical features of the patient.

In total shoulder arthroplasty, the guide wire is a commonly used pieceof hardware that is drilled into bone to define the axis and location ofa hole that can be drilled into the glenoid in order to affix theglenoid component of the joint prosthesis into place. Once in position,the guide wire is drilled over with a cannulated drill bit and removedto create the hole for the implant stalk. In this way the axis andposition of the implant stalk is consequentially defined.

In the embodiments shown in FIGS. 2 to 7, guide blank 14 is providedincluding modifiable or moldable element 16, and rigid carrier 18 forcarrying moldable element 16.

Guide blank 14 can also be referred to as a registration tool since itcan be registered to a production apparatus and anatomical features of apatient.

Guide blank 14 is later on in the workflow inserted into and adapted byproduction apparatus 20 (shown for example in FIG. 3) which is able tomodify guide blank 14 to rapidly form a bespoke guide to facilitate theplacement of guide wire 12.

Moldable element 16 can be a temporarily moldable element made up, forexample, of a material that, once activated, is initially pliable andcan eventually harden over time or in the presence of a catalyst orother setting initiator such as a bright light of particular wavelengthor exposure to atmospheric air. In other embodiments, moldable element16 can be a non-hardening moldable material, although in someembodiments this is not preferred since there can be a risk of moldableelement 16 being undesirably deformed during further processing.

The moldable material is contained, retained, and incorporated withinthe carrier.

Moldable element 16 can be molded by being pressed into a surgical site,after which it can be considered to be an impression element, as it canprovide an impression of the surgical site.

Carrier 18 includes a coupling arrangement by which guide blank 14 canbe coupled into production apparatus 20 in a predetermined position.

In the embodiments shown in FIGS. 2-7, the coupling arrangement includesguides in the form of channels 22 which can receive counterpart guidesin the form of ridges in order to couple guide blank 14 to productionapparatus 20. In other embodiments, the coupling arrangement can includea clip or other attachment mechanism.

In the embodiments shown in FIGS. 2-7, carrier 18 is a standardizedcomponent that has features that are compatible with features ofproduction apparatus 20. By providing carrier 18 as a standardizedcomponent, it is easier to ensure, or at least increase the likelihood,that carrier 18 easily fits into a receptor assembly of a productionapparatus in a known predetermined position.

Carrier 18 can incorporate additional features such as finger rests,grips 24, or fixings for additional associated instrumentation.

In some embodiments, a variety of sterile pre-packaged guide blanks canbe offered, compatible with and reflecting the various sizes of surgicalsites that surgeons face. For the embodiment shown in FIGS. 2-7, a guideblank of the appropriate size and shape for the purpose of a shoulderreplacement will be selected. In this case, one that is roughly theshape of the average human glenoid cavity.

In the embodiment shown in FIGS. 2-7, production apparatus 20 includesthe following elements as shown in FIGS. 3 and 4:

scanner 26 to create a detailed 3D surface scan of an object. This canfor example be an optical 3D scanner;

receptor assembly 28 capable of receiving guide blank 14;

adjustment mechanism 30 operable to manipulate and the position ofreceptor assembly 28 (and thereby also a guide blank received in thereceptor assembly) with respect to modification tool 32;

modification tool 32 capable of independent movement with respect toreceptor assembly 28 (and thereby also with respect to a guide blankreceived in the receptor assembly) and operable to modify guide blank 14when received in receptor assembly 28;

control unit 34, such as a microprocessor control unit, designed,suitably connected and powered such that it can control the functioningof production apparatus 20; and/or

communication element 36, for example with wireless connectioncapabilities, such that the production apparatus can be given externalcommands by an operator and obtain data.

It is not necessary to have adjustment mechanism 30. In some embodimentsmodification tool 32 can provide the necessary relative movement.

Scanner 26 is arranged to face receptor assembly 28 thereby to be ableto scan impression element 16 of guide blank 14 received therein.

Adjustment mechanism 30 is configured to manipulate and orientate theposition of receptor assembly 28 (and thereby also a guide blankreceived in the receptor assembly) with respect to scanner 26 to enablescanner 26 to scan most of, if not the entire, surface of impressionelement 16 and in some embodiments to scan at least a part of carrier18.

Control unit 34 is calibrated with the relative position of the scannerwith respect to at least one reference point. In some embodiments, thereceptor assembly provides a reference point although reference pointscan be provided by other parts of the production apparatus. In someembodiments, the receptor assembly does not provide a reference pointbut is itself calibrated with respect to the one or more referencepoints.

Control unit 34 can therefore determine from a scan by the scanner theposition of the impression element of a guide blank in the receptorassembly with respect to the one or more reference points of theproduction apparatus, thereby registering the impression element to theproduction apparatus. In the embodiment shown in FIGS. 2-7, becausecarrier 18 is a standardized component, that is to say it has apredetermined configuration, and is received only in a predeterminedposition in the receptor assembly, the guide blank, including thecarrier, is effectively registered to the production apparatus.

As described above, control unit 34 is operable to control the positionof receptor assembly 28 using adjustment mechanism 30, for example toenable the whole of the impression element to be scanned. The controlunit is configured to compensate for such movements of the receptorassembly when registering the impression element with the productionapparatus.

The control unit is also calibrated with the relative position of themodification tool with respect to the one or more reference points andthereby with respect to the production apparatus. Once the impressionelement has been registered to the production apparatus, the controlunit can therefore also determine the position of the modification toolwith respect to the impression element, enabling the control unit tomanipulate the modification tool and the adjustment mechanism to make adesired modification to a guide blank.

In some embodiments, as components within the production apparatus moverelative to each other, for example as a result of movement of themodification tool or operation of the adjustment mechanism, control unit34 is configured to adjust its calibration.

As described above, the modification tool is movable with respect to thereceptor assembly. The modification tool can be moved to come intocontact with a guide blank in the receptor assembly whereby to modifythe guide blank in a controlled manner.

The modification tool can for example include a CNC drill, cuttingdevice or other modifier, depending on the type of modification to bemade to the guide blank. In some embodiments, the modification tool doesnot structurally modify the guide blank, but simply marks it. In suchembodiments, the modification tool can include a marker to mark theguide blank to show where structural modifications should be made, andthese structural modifications can be made subsequently by hand.

Production apparatus 20 is a sealed self-contained, reusable unit. Forthis reason, parts of the production apparatus that comes into contactwith material that will touch human tissue should be easily disposed ofand replaced in order to maintain sterility.

As described above, the production apparatus includes receptor assembly20 into which guide blank 14 is able to be attached once it has receivedan impression of a surgical site. In some embodiments, receptor assembly20 is located centrally within the production apparatus, although otherpositions are possible.

Once the patient's anatomy has been suitably dissected in the usualfashion to expose the surgical site, in this case the glenoid cavity asshown in FIG. 1, guide blank 14 is used to begin the guidance process.

The deformable area of guide blank 14—moldable element 16—is suitablyactivated while guide blank 14 is firmly pressed into the glenoid cavityallowing the deformable surface to mold to the shape and form animpression of the glenoid cavity and any exposed edges. This process canbe seen in FIG. 6. Position 100 shows guide blank 14 being pressed intothe surgical site to form an impression. In some embodiments, it ispreferable to have as much contact as possible between the moldable areaof the guide blank and the bony anatomy that can be safely exposed.

Once moldable element 16 has set and become a firm impression element,guide blank 14 with integral moldable element, having been molded to theshape of the glenoid, can be removed from the surgical field and thenext stage of the process can begin.

In order to aid later relocation of the guide blank, provision can bemade for screwing or pinning of the guide blank into place, perhaps atthe time that the moldable material is setting.

Guide blank holder 38, which in some embodiments can be referred to asan enclosure lining, is then inserted into receptor assembly 28 of theproduction apparatus. In some embodiments, guide blank holder 38 issingle use and sterile and includes guide blank coupling element 40 tocouple a guide blank into the guide blank holder 38 in a predeterminedrelative position so that the guide blank is received in receiving zone41 without contact with the production apparatus. In the embodimentsshown in FIGS. 2-7, the guide blank coupling element includes channel 43including first and second ridges 42 for coupling to first and secondchannels on carrier 18 of guide blank 14, although other coupling orattachment mechanisms can be used in other embodiments.

The guide blank holder also includes at least one receptor assemblycoupling arrangement for coupling the guide blank holder into a holdercoupling arrangement of the receptor assembly so that the guide blankholder is held in a predetermined relative position without the guideblank contacting the production apparatus. In the embodiments shown inFIGS. 2-7, the at least one receptor assembly coupling arrangementincludes first and second flanges 44 for being received in a holdercoupling arrangement including first and second channels 46 of thereceptor assembly.

In the embodiment shown in FIGS. 2-7, guide blank holder 38 is astandardized component and control unit 34 is calibrated with dimensionsof guide blank holder 38 and carrier 18 whereby control unit 34 iscalibrated with the relative position of carrier 18 and holder 38 withrespect to the one or more reference points, and thereby to theproduction apparatus, when inserted into the receptor assembly.

Guide blank 14 is inserted into receptor assembly 28 of productionapparatus 20, in particular into guide blank holder 38, itself separatefrom, in the sense of non-integral with and removable from, theproduction apparatus assembly.

Guide blank 14 is fastened into place in a fixed predetermined positionwith respect to the receptor assembly as defined by the standardizedconstruction of both the receptor assembly and the guide blank holder.In other words, when inserted into the guide blank holder, the carrierof the guide blank is in a predetermined position with respect to thereceptor assembly.

While the surfaces of the receptor assembly are not sterile, the guideblank holder is placed into the aperture by a sterile agent such thatwhen it is affixed within the production apparatus, the surfaces of theguide blank holder not in contact with the production apparatus remainsterile. Guide blank 14 can now be inserted into its correspondingcoupling element 40 in the guide blank holder and also remain sterile asshown in FIG. 5.

Once the prepared guide blank has been affixed in the above way, theassembly including the production apparatus, guide blank holder andguide blank is now initiated.

Microprocessor control unit 34 of the production apparatus now canwirelessly or otherwise connect via communication element 36 with one ormore computers including the digital plan and the medical imaging datarelating to the particular patient such as CT scan data. For example,this can be the computer used by the surgeon to plan the procedure theywish to undertake. The digital plan or prescription for the operationcan be downloaded into control unit 34 of the production apparatus.

Guide blank 14 is anchored in place within guide blank holder 38 inreceptor assembly 28 such that impression element 16 faces towards 3Dsurface scanner 26 within the production apparatus.

The 3D surface scanner is mounted in a fixed position thus themicroprocessor is programmed with an inherent knowledge of the spatialrelation between the surface scanner and the position of the receptorassembly containing the guide blank holder and the guide blank.

The surface scanner scans in the direction of impression element 16 ofguide blank 14, thus forming a 3D surface model of impression element16. If required, the receptor assembly can manipulate guide blank 14 inseveral axes, with the use of integrated servo motors or otherwise, forexample using adjustment mechanism 30, to maximally expose most, if notall, surfaces of the impression element to the scanner.

Because control unit 34 is calibrated with the relative positions of thescanner and the one or more reference points, control unit 34 candetermine the relative position of the impression element with respectto the one or more reference points and can thereby co-register the 3Dsurface topography of the impression element with the productionapparatus. Because in this embodiment carrier 18 and guide blank holderare standardized components, control unit 34 can register the impressionelement with the carrier and with the guide blank holder. The controlunit can also register the impression element with the receptor assemblywithin the production apparatus.

This co-registration is facilitated by the interposition of 3D data fromthe scanner alongside the pre-determined geometry of the carrier, guideblank holder and production apparatus assembly with respect to the 3Dscanner. This process can be further explained if the impression elementwere to be removed from the guide blank such that only carrier 18 wereto remain affixed within the guide blank holder within the productionapparatus; the scanner would produce 3D data identical to itspre-programmed ‘knowledge’ of the geometry within the productionapparatus regardless of the spatial configuration of the assembly. Ifthe impression element is now added, the scan will produce data with a‘body’—the impression element, obscuring the aforementioned ‘standardgeometry picture’ that would have been seen from the point of view ofthe 3D scanner. The distance from the scanner surface to points of theimpression element surface will inherently be calculable thus this datacan be used to produce a virtual model ‘within’ the production apparatusprocessor, of the position and shape of the impression element surfacewith respect to the carrier of the guide blank, the guide blank holderand the production apparatus aperture assembly; thus spatiallyregistering the geometry.

To be surgically useful, the components should be co-registered withanatomical features of patient anatomy as defined by pre-operative imagedata. A computer program is executed either on an associated computer orthe inbuilt processor within the production apparatus. This programanalyses the 3D scan data of the impression element and compares it tothe imported CT scan data in the following way. It is given that themajority of the impression element will be the impression caused bypressing the impression element to the native bony anatomy within thesurgical field; in the case of this embodiment, that of the glenoidcavity (FIG. 1) surface. An individual's bony anatomy is unique isshape, in addition to this, wear and tear has often removed the majorityof the cartilage from the surface of the joint and osteoarthritis hasdeformed the surface into a topographically unique geometry. In the caseof the total shoulder arthroplasty (TSA), the glenoid labrum is alsoremoved and the anterior rotator cuff muscles are released, thusexposing the distinct anterior edge of the glenoid. With appropriatecommonplace medical imaging software, it is possible to isolate only thebony anatomy from the pre-operative imaging data and produce a virtual3D model. The program then runs an algorithm that matches the scannedsurface of the impression element, with the corresponding anatomyobtained from the processed pre-operative imaging data. Advantageously,the initial pre-operative imaging of the patient can be done before thesurgery begins, possibly days or weeks before. Some portion of anyimpression on the impression element caused by bony anatomy from thesurgical field will have a matching topographical area on thepre-operative imaging data. The algorithm identifies these matchingsites over as large an area as possible. For the purposes of thisembodiment, it is assumed that this process can be externally assistedif, for example, the operator virtually ‘colors-in’, or otherwiseindicates, specific areas on the virtual bony anatomy model, from whichthey will plan the case, that they are sure will form at least a part ofthe impression element surface. For example, at the time of surgery, thesurgeon can roughly color in these corresponding areas on the moldedsurface of the impression element with a sterile marker pen. This willassist the algorithm as it will roughly highlight areas that should benear-by each other if it is imagined that the impression element couldbe brought together with ‘virtual’ 3D model of the patient's anatomy.‘Registration’ algorithms used to co-register data representing asurface configuration with preoperative imaging data are known.

Due to the molding procedure of the moldable element, the guide blankcan only be fitted back into the surgical field in the same position atwhich it was first molded as a result of its unique fixed topography.The above algorithm co-registers the impression element with the uniquearea of anatomy onto which it fits. Through the aforementioned processthe impression element has also been co-registered with the carrier,with the guide blank holder, and with the production apparatus. Thus,the guide blank is now precisely positionally defined with respect tothe patient anatomy and within the production apparatus. Of course, thepositional definition of the impression element or guide blank withrespect to the patient anatomy defines the position if the impressionelement were to be placed back at the surgical site, whereas theposition definition with respect to the production apparatus defines theposition in the receptor assembly. Put another way, the carrier of theguide blank has been spatially registered with the scanned surface ofthe impression element but at the same time the impression element hasnow been registered with the patient anatomy from which it was molded.The result of this process ensures, or at least increases thelikelihood, that if, at this point, the guide blank is placed back intothe surgical field in the identical position from whence it was molded;the software will ‘understand’ the spatial orientation and position ofthe carrier and the impression element with respect to the patientanatomy and be able to generate a 3D ‘virtual’ model of the guide blankin situ on the bony anatomy as illustrated in FIG. 6.

Guide Creation

In this embodiment, the elements have been set up for the purpose ofguiding the orientation and position of the axis through which to placeguide wire 12 (FIG. 1) to facilitate the correct positioning of theglenoid component of the total shoulder replacement. As previouslydescribed, the production apparatus also houses a modification tool, inthis embodiment CNC drill 32 (FIG. 3 and FIG. 4) situated on theopposite end of receptor assembly 28 to 3D scanner assembly 26. CNCdrill 32 can, however, be positioned in convenient positions within theproduction apparatus. Drilling assembly 32 includes motor 50 capable ofpowering rotating sterile drill bit 48, and apparatus to orientate theposition of the drill assembly with respect to the guide blank once theguide blank has been mounted within the guide blank holder withinreceptor assembly 28.

Motor assembly 50 is provided with an aperture into which can be fittedsterile drill bit 48, sterile drill bit 48 being of diameter just largerthan the diameter of selected guide wire 12. The drill can for examplebe provided with a quick release assembly. The guide blank should remainsterile as it will eventually be placed back into the surgical field.For this reason, when the apparatus is used on a new patient, newlysterilized drill bit 48 is placed into drilling apparatus 32 of theproduction apparatus before use. The working shaft of drill bit 48remains sterile as it will not come into contact with other structuresother than the sterile guide blank mounted above it.

In this embodiment, drill assembly 32 is capable of translation in theX, Y and Z axes of the plane of scanner 26 while adjustment mechanism 30is capable, using a second motor, of rotating the affixed guide blank inthe X and Y axis. The method described here for the movement of theguide blank and modification tool can be substituted for methods ofmovement used on existing or future devices such as CNC devices. Boththe translational movements of CNC drill 32 and rotation of receptorassembly 28 can be unpowered in a different embodiment. As analternative to computer controlled positioning, movement can becontrolled via the turning of, for example, a graduated dial in order toposition and lock a particular axis into a position specified by acomputer.

The axis and position through which the surgeon would like to drill intothe glenoid cavity to facilitate placement of the glenoid componentguide wire is previously specified by the surgeon in the preoperativedigital operative prescription or digital plan.

Control unit 34 is configured to use the co-registration of theimpression element with anatomical features at the surgical site toconvert the digital plan into a plan for the impression element.Effectively, the co-registration of the impression element withanatomical features at the surgical site allows the impression elementand anatomical features at the surgical site, and therefore the digitalplan, to be expressed in the same frame of reference as if theimpression element were in place at the surgical site, and therebyallows the digital plan to be converted into a plan for the impressionelement. The plan for the impression element indicates how theimpression element should be modified to form a guide to comply with thedigital plan, so that the guide can guide the surgery according to thedigital plan when the guide has been placed back into the surgical sitefrom which the original impression was taken. For example, in theembodiments shown in FIGS. 2-7, the plan for the impression element is aplan for hole 52 through the impression element to accommodate guidewire 12, as shown in FIG. 7.

The control unit is also configured to convert the plan for theimpression element into modification instructions, the modificationinstructions being instructions for adjustment mechanism 30 andmodification tool 32 in order to modify the guide blank in accordancewith the plan for the impression element. The control unit is configuredto convert the plan for the impression element into modificationinstructions using the registration of the impression element withrespect to the production apparatus. The control unit can express theimpression element, and therefore the plan for the impression element,in the same frame of reference as the production apparatus and canthereby determine modification instructions of how to operate theproduction apparatus to follow the plan.

The modification instructions provide control instructions to theproduction apparatus to operate the drilling apparatus and manipulatethe position of the guide blank with respect to the drilling apparatussuch that a guiding hole can be drilled through the guide blank thatsatisfies the positional and axial constraints specified in theoperative prescription. The aforementioned registration steps ensure, orat least increase the likelihood, that the hole drilled is positionallyand axially equivalent to the position of the virtual guide wire withrespect to the glenoid from the post-operative plan.

Once the control unit has determined the modification and/or controlinstructions, it operates the production apparatus in accordance withthose instructions to modify the guide blank held in the receptorassembly. The guide blank is now a guide and can be removed from theguide blank holder within the production apparatus cavity and placedback into the glenoid cavity in its fixed position as defined by the nowsolid impression element. If need be, the guide can be secured in placewith some accessory pins, alternatively it can be held in place withapplied pressure by the surgeon or an assistant. The surgeon can nowdrill guide wire 12 through the hole created in the guide as shown inFIG. 7, with the knowledge that the position and orientation at whichthe guide wire will pass into the glenoid surface will be identical tothe pre-operative virtual plan previously specified. Clean passage ofthe guide wire or surgical drill can be facilitated by previouslyinserting a suitable sleeve through the prepared hole. Any swarfremaining after the drilling procedure can be washed away before use,alternatively the CNC drill apparatus can be provided with a suction orwasher system capable of ensuring no swarf remains at the drilling site.

Once the guide wire insertion process has been completed, the drill canbe removed from the end of the fixated guide wire and guide 14 can beslid off the wire, leaving guide wire 12 in place, satisfying thepre-determined positional constraints previously laid out by the surgeonin the operative prescription. At this juncture the procedure can nowcontinue as normal, with the knowledge that the glenoid component willbe affixed in the optimal orientation possible as defined by guide wire12.

FIG. 12 shows guide blank holder 1038 and carrier 1018.

As can be seen, in this embodiment, carrier 1018 includes plateau 1019which in this embodiment includes narrow region 1020 and wide region1021, with sides of plateau 1019 tapering from wide region 1021 tonarrow region 1020, plateau 1019 having rounded edges.

Plateau 1019 includes a plurality of spikes for receiving and couplingcarrier 1018 to moldable material.

Carrier 1018 includes first foot 1023 mounted on plateau 1019 on theopposite surface from spikes 1022 in the region of narrow region 1020,and second and third feet 1024, 1025 mounted on the opposite surface ofplateau 1019 from spikes 1022 in the region of wide region 1021.

The first, second and third feet are mounted to legs which depend fromthe plateau. First foot 1023 includes a capture element including firstand second protrusions joined by wall 1026 which extends only part theway along the protrusions, so that the protrusions for part of theirlength are joined by wall 1026, and for part of their length have a gapbetween them.

Guide blank holder 1038 includes perimeter wall 1039 which extendssubstantially straight along lateral walls and includes curved frontwall 1040 but has an open back, top, and bottom. Lip 1041 extendsoutwardly from a base of perimeter wall 1039.

First retaining element 1042 is attached to the perimeter wall adjacentto front wall 1040. First retaining element 1042 includes recess 1043into which the first and second protrusions of first foot 1023 ofcarrier 1018 can be placed and obstruction element 1044 arrangedadjacent to recess 1043 to obstruct wall 1026 of carrier 1018 when foot1023 of carrier 1018 is in recess 1043. Recess 1043 is bordered by awall. This wall has an opening facing obstruction element 1044.

Guide blank holder 1038 also includes first and second food rests 1045disposed so that second and third feet 1024, 1025 of carrier 1018 canrest upon them when first foot 1023 of carrier 1018 is coupled withretaining element 1042. First and second foot rests 1045 are positionedadjacent to the open back end of guide blank holder 1038.

When carrier 1018 is to be inserted into guide blank holder 1038, firstfoot 1023 is placed into retaining element 1042 so that the first andsecond protrusions are disposed in recess 1043 and retained therein onthree sides by the wall of the recess. Carrier 1018 is prevented, or atleast deterred, from leaving recess 1043 via the opening in the recessowing to the obstruction of movement of wall 1026 by obstruction element1044.

The second and third feet of carrier 1018 rest upon foot rests 1045. Thecarrier is then held in receiving zone 1050 in the guide blank holder,protected by perimeter wall 1039.

When placed into production apparatus 1020 such as shown in FIG. 13, lip1041 of guide blank holder 1038 couples with a channel in receptorassembly 1028 of the production apparatus in a predetermined positionwithout the carrier coining into contact with the production apparatus.

FIG. 14 shows modification tool 1032 in production apparatus 1020.

The embodiment of FIG. 12 is particularly advantageous as the carriercan be clipped into the guide blank holder with one hand.

The processing or software described herein, such as the registration ofelements, and the calculation of modification instructions, can beperformed by control unit 34 itself or can be performed by an externalcomputer.

The above described embodiments provide a method specifically for theplacement of a guide wire into the glenoid cavity during the TSAprocedure.

Other embodiments can be used for other surgical procedures.

Embodiments of the guide can be produced such that they are specificallydesigned for certain procedures. An example might be a guide designed tofacilitate the positioning and orientation of the acetabular componentin total hip arthroplasty surgery as shown in FIG. 8. In thisembodiment, impression element 16′ of guide 14′ is produced such that itis bulbous in structure similar to that of the femoral head, so as tosupport the moldable material, and to minimize, or at least reduce, theamount of material needed.

A range of sterile, pre-packaged guide blanks can be provided reflectingthe various sizes of acetabulum that can be presented.

Once moldable element 16′ has been activated, the guide blank can bepressed into acetabulum 60, ensuring that moldable element 16′ conformsto the unique topography of the intraoperatively exposed bone. Oncemoldable element 16′ has been modified in this way, the process cancontinue in the manner described in the previous embodiment in order toproduce a guide.

The production apparatus can be designed such that it will accommodateguide blanks of differing types reflecting the different types ofoperation in which they might be used. All guide blanks might have anidentical standardized carrier where practical. The moldable elementwill vary in initial design and size to accommodate differingapplications.

Embedded RFID tags, bar, or QR codes can identify various aspects of thepatient and procedure, such as patient name, operation side, digitalplan, and component sizing to the software.

The following describes one design for the moldable element of the guideblank, although other designs and materials can be used in otherembodiments. Moldable element includes two constituent parts and isshown in FIG. 9A. Outer layer 62 that will come into contact withpatient anatomy includes a low temperature thermoplastic. Layer 64immediately below outer layer 62 is formed from a permanently deformablematerial with a consistency suitable to provide mechanical support tooutermost thermoplastic layer 62. This material is pre-formed in aconfiguration such that that it can fit the general shape of theanatomical area to which the guide blank is designed to be molded. Thisdictates the general shape of the as yet unformed thermoplastic layer62. Moldable element 16 is mounted on carrier 18 of guide blank 14.

To activate guide blank 14, an infrared heated receptacle can beprovided associated with or as part of the production apparatus. Theselected guide blank can be placed into the aforementioned receptacleand the thermoplastic surface heated to its transition temperature. Atthis point, the production apparatus can set itself up to shortlyreceive the molded guide blank, for example, by selecting the correcttool from an internal library for the imminent modification of theprepared guide blank. The thermoplastic that is selected for outer layer62 has a transition temperature lower than that of the tissue damagingthreshold. Once sufficiently heated the guide blank is held by thecarrier and the moldable element is pressed onto the anatomical area ofinterest thus allowing thermoplastic layer 62, supported by deformablematerial layer 64 underneath, to take the shape of the underlyinganatomy before, once again, becoming solid as shown in FIG. 9B.

In another embodiment, moldable element 16″ and carrier 18″ begin theprocess as separate entities as shown in FIG. 10. A sterilebiocompatible, rapid setting polymer 70 is provided in sterile syringe72. Carrier 18″ has features 22 that allow it to be slotted into theaforementioned guide blank holder and on its reverse surface it possessbarbed members 74 that generate adhesive forces if the member is pressedinto rapid setting polymer 70. The surgeon injects polymer 70 onto thesurface of the dissected joint or bony anatomy and can roughly shape itinto a globular body. Sterile carrier 18″ is then pressed into theglobular body as it sets hard such that the barbed surface of carrier18″ will end up solidly held in the body of the polymer so that theglobular body forms moldable element 16″. The guide blank holderinterfacing surface of the carrier remains exposed. In this way, oncefully set, this guide blank can be removed from the surgical field andwill include a body of solid polymer that has been molded to thetopography of the chosen bony anatomy and a carrier geometrically fixedin position with respect to the molded surface. From this point, theprocess can now continue in the same manner as has been previouslydescribed.

In a further embodiment, the guide blank can consist solely of a body ofmoldable material without a carrier. The moldable material in such anembodiment is sterile and able to ‘set’ to become hardened. A sterileguide blank holder is provided with, for example, spiked hinged memberssuch that the now set body of moldable material is able to be securelyfastened into the guide blank holder. As there is no carrier in thiscase the body is affixed into the guide blank holder such that itsmolded face is in view of the scanner. The body is now fixed withrespect to the guide blank holder which is itself geometrically fixedwith respect to the rest of the production apparatus. The scanner nowscans the surface of the body thus geometrically registering it withboth the preoperative CT scan and the production apparatus. The body cannow be modified in the above described manner and placed back into thepatient to act as a guide.

The guide blank can be modified such that it is capable of guiding amultitude of different surgical processes. Modifications might includeholes for guide wires as described above, but can include other guidanceor navigational structures. Options might include slots to cut groovesor section pieces of bone in operations such as the total kneereplacement or to dictate angle and position for the removal of theproximal humeral head in TSA surgery.

Another embodiment is shown in FIGS. 18 and 19. FIG. 18 shows guideblank 2014 corresponding in many respects to the guide blank shown inFIGS. 2-7. Carrier 2018 includes a coupling arrangement including guidesin the form of channels 2022 similar the embodiments shown in FIGS. 2-7.In this embodiment, channels 2022 are provided on first and second rails2023 which are part of the surface of carrier 2018. However, channels2022 work in substantially the same way as channels 22 described above.

Carrier 2018 has a predetermined configuration and is rigid so as tomaintain that predetermined configuration during molding of the moldableelement and scanning.

In this embodiment, carrier 2018 includes a reference element orfiducial marker 2100 in the form of a T-shaped lateral projection fromcarrier 2018. As with other embodiments, in this embodiment, carrier2018 is arranged opposite a surface of moldable element 2016 which willbe scanned. Fiducial element 2100 is configured to project laterallybeyond moldable element 2016 so that a scan of the surface of themoldable element opposite carrier 2018 will include a scan of fiducialelement 2100. With knowledge of the configuration and position of thefiducial element with respect to body 2015 of the carrier, the positionof carrier 2018 as a whole with respect to moldable element 2016 can beobtained from the relative position in the scan of fiducial element2100.

In this embodiment, carrier 2018 includes a guiding element couplingarrangement for coupling carrier 2018 to a guiding element. In thisembodiment, the guiding element is sterile programmable tool 2200 asshown in FIG. 19. However, in other embodiments, the guiding element canbe other elements for guiding a surgical component to interact with apatient.

In this embodiment, the guiding element coupling arrangement includes aplurality of recesses 2102 for receiving respective feet 2202 of guidingelement 2200. In this embodiment, there are four recesses for four feetof the guiding element as this provides a stable coupling. However, adifferent number can be included in other embodiments.

Each of recesses 2102 includes alignment block 2104 to be received inalignment recess 2204 of the respective guiding element foot in order tomaintain the guiding element, or at least those parts of the guidingelement that are fixed with respect to feet 2202, in a desiredpredetermined position with respect to carrier 2018. As is describedbelow, some components of the guiding element can be movable for exampleto allow the guiding element to be placed into one of a plurality ofdifferent configurations.

As shown in FIG. 19, guiding element 2200 includes four feet 2202 tocouple with four recesses 2102 on carrier 2018. Each of feet 2202 iscoupled to leg 2206 which depends from body 2208 of guiding element2200. In this embodiment, the body and feet are fixed with respect toeach other. The body of the guiding element includes tool guide 2210which can be positioned in one of a plurality of configurations. Inother words, it is programmable. In this embodiment, tool guide 2210 isa drill guidance tube which passes through body 2208 of guiding element2200. In other embodiments, tool guide 2210 can be a guide for differenttypes of tools, for example can include a reconfigurable slot throughwhich a cutting tool can operate.

In this embodiment, guiding element 2200 includes first and second dials2212 to orientate tool guide 2210 in two mutually perpendicular axes inorder to position tool guide 2210 in a desired one of the plurality ofpossible configurations. These dials 2212 are designed to be adjusted bythe surgeon by hand. In other embodiments, tool guide 2210 can beautomatically reconfigured.

In some embodiments, guiding element 2200 can include a surgical tool tobe guided by tool guide 2210 and in other embodiments tool guide 2210can be for guiding a separate tool.

In operation, moldable element 2016 becomes an impression elementproviding an impression of a surgical site in the same manner asdescribed above. The impression element is scanned and registered withanatomical features of the patient's anatomy by software, again asdescribed above. However, in this embodiment, because of guiding element2200 it is not necessary to modify the impression element and carrier inorder to form a surgical guide. In this embodiment, impression element2016 is registered with carrier 2018 using the presence of fiducialelement 2100 in the scan of impression element 2016. As described above,from the position of fiducial element 2100 in the scan, the position ofpart of, if not the entire, carrier 2018 with respect to the scan can bedetermined, and carrier 2018 as a whole can be registered to impressionelement 2016. It is therefore not necessary in this embodiment for thecarrier to be clipped into a production or registration apparatus, sincethe registration is performed from one scan. A surgeon or a surgeon'sassistant simply scans the impression element and fiducial element, forexample by a handheld 3D optical scanner.

On an electronic level, what is happening is that data representing theconfiguration of carrier 2018 is registered with surface data from thescan representing the surface configuration of impression element 2016.

Once carrier 2018 has been registered with impression element 2016,guiding element 2200 can be registered with impression element 2016. Inother words, data representing the structure of the guiding element canbe registered with the surface data representing the configuration ofthe surface of impression element 2016. The data representing thestructure of the guiding element can include data representing apredetermined configuration with respect to carrier 2018 of those partsof guiding element 2200 which are fixed with respect to the carrierafter coupling and data representing the configurability of thereconfigurable parts of the guiding element. In other embodiments, thedata representing the structure of the guiding element can include datarepresenting each of the possible configurations of the guiding elementwith respect to the carrier after coupling. The data representing thestructure of the guiding element can be registered with the surface datausing the registration of carrier 2018 with impression element 2016.

Guiding element 2200 can then be registered with anatomical features ofthe patient's anatomy. In other words, the data representing thestructure of guiding element 2200 can be registered with features ofimage data representing features of the patient's anatomy, for examplefrom pre-operative imaging data. This can be done using the registrationof guiding element 2200 with impression element 2016, and theregistration of impression element 2016 with the anatomical features ofthe patient.

With guiding element 2200 registered with anatomical features of thepatient, the software determines a desired configuration of tool guide2210 in order to guide a tool to form a surgical interaction with apatient which is in accordance with the surgical plan.

In this embodiment, body 2208 of the programmable tool is inherentlyregistered with carrier 2018 as it is only able to be clipped in in oneway. Impression element 2016 is registered to patient anatomy in themanner discussed above. The impression element is then registered tocarrier element 2018 using the fiducial marker. Impression element 2016is now inherently registered with body 2208 of the programmable tool byvirtue of the fact they are both registered to carrier 2018. Asdescribed above, once anatomical registration has been carried out, thedigital plan can now be expressed in the frame of reference ofimpression element 2016 and carrier 2018 and, as previously, be used tocreate a modification plan. In this embodiment, programmable tool body2208 is registered with respect to the impression element and thecarrier so the digital plan can now be expressed in the same frame ofreference as programmable tool body 2208. The computer software ispre-programmed with an inherent ‘knowledge’ of the dynamics of toolguide 2210 with respect to tool body 2208 as facilitated by programmingdials 2212, thus, the software can now calculate an appropriateconfiguration or transformation such that tool guide 2210 axis andposition is identical to the axis and position of the axis of thedigital plan. It is to be noted that this axis can also be describedwith respect to the impression element or carrier 2018. Once anatomicalregistration has been carried out, the coordinates describing thegeometry of the digital plan with respect to the patient anatomy canalso be described with respect to the impression element and carrier.

The software now converts this configuration or transformation into thenumerical values to which programmable tool control dials 2212 arerotated such that tool guide 2210 matches the axis and placement of theappropriate drilling axis in the real world. A surgeon or assistant cannow rotate the dials to the appropriate value. This ensures, or at leastincreases the likelihood that, the programmable tool is clipped ontocarrier 2018 in appropriate recessions 2102 and the surgeon drillsthrough tool guide 2210 into the patient anatomy (in this embodimentpassing through the carrier and impression element) thus placing a guidewire or pin in the identical geometrical configuration as defined by theplan.

This embodiment therefore has the advantage that it does not require aproduction apparatus, and does not require direct modification of theimpression element, but can use a standardized programmable tool andregister most, if not all, the components together using a simplehandheld scanner.

The embodiment of FIGS. 18 and 19 can be provided without fiducialelement 2100, and the registration can be performed in a registrationapparatus that corresponds in many respects to the production apparatusdescribed above; however, the production apparatus in such an embodimentdoes not need a modification tool.

In some embodiments, guide element 2200 can be an integral part ofcarrier 2018. Furthermore, the guide element does not need to beprogrammable, but can be provided in a fixed predetermined location withrespect to carrier 2018 to allow a reference marker to be attached to apatient's anatomy for guidance or navigation for further surgery. Forexample, in FIG. 8, the carrier can include holes 80 in arms 84 or otherextending members for the placement and registration of guide pins orscrews 82 that can, themselves, orientate other surgical equipment.Carrier 14′ is registered with anatomical features of the patient in themanner described above. Since holes 80 and arms 84 are in apredetermined position with respect to the body of the carrier, they aretherefore also registered with the anatomical features of the patient.The standard hole in carrier 80 defines the axial position of the screwor pin and associated flanged screw driver 86 can drive the screw intothe bone until flange 88 comes into contact with the top of guidancehole 80, thus limiting the distance that the screw or pin can be driveninto the bone. Once these guide pins 82 are in place, separate apparatuscan be placed over the pins such that it will also be inherentlyregistered to patient anatomy and the original guide can be discarded.This process allows the joint surface to be fully exposed whileintraoperative guidance can still be used as the fixed members screwedinto nearby bone will be registered to patient anatomy. In this manner,standardized surgical guides can be positioned in a patient specificmanner thus allowing the precise placement of standardized cuts or holesin, for example, a knee replacement procedure.

FIG. 20 shows an example of such separate apparatus that can be placedover the pins so that it will be inherently registered to anatomicalfeatures of the patient's anatomy.

FIG. 20 shows programmable guiding element 3000 including pin sleeve3002 and tool guide 3004. Tool guide 3004 can be positioned in one of aplurality of positions with respect to pin sleeve 3002. In thisembodiment, tool guide 3004 is a drill guide, however in otherembodiments other tool guides can be provided.

In this embodiment, tool guide 3004 is mounted on a stalk which iscoupled to pin sleeve 3002 by ratcheted pivot mechanism 3006 whichallows stalk 3005 to be positioned at one of a plurality of angles withrespect to pivot 3006. In this embodiment ratcheted pivot 3006 includesdial 3008 marked with positions such as angles so that the surgeon canposition stalk 3005 at the desired angle.

The ratcheted pivot 3006 does not need to be ratcheted in everyembodiment, but it is provided with a means to hold the stalk in adesired position.

In addition, pin sleeve 3002 includes first and second mutuallytwistable components and markings to show the extent of twist.Accordingly, in this embodiment, by appropriate twisting of the pinsleeve and movement of the stalk, tool guide 3004 can be placed in aplurality of different configurations, each configuration providing thetool guide in a different position with respect to a pin in the pinsleeve.

Pin sleeve 3002 includes internal passage 3010 for receiving a pin suchas pin 3012 shown in FIG. 20. In this embodiment, passage 3010 and pin3012 are asymmetric so that pin sleeve 3012 will only fit over pin 3012in one orientation, thereby ensuring that guiding element 3000 ispositioned on pin 3012 in a known predetermined manner. In thisembodiment, this is achieved by pin 3012 including flange 3014 andpassage 3010 including corresponding channel 3016 for receiving flange3014. However, in another embodiment, a carrier can be designed similarto the depiction in FIG. 8 however it will guide the placement of twoplanar pins. In this way, flanged pins need not be used as aprogrammable object possessing two pin sleeves can be used and slid overboth pins thus locking the body both positionally and axially.

In use, once the carrier and impression element of FIG. 8 have been usedto position a pin such as pin 3012 in a known position and configurationwith respect to anatomical features of the patient's anatomy, pin sleeve3002 of guiding element 3000 is positioned over pin 3012. Owing to thepredetermined structure and adjustability of guiding element 3000, orthe pre-calibrated possible configurations of guiding element 3000,guiding element 3000 can thereby be registered to the anatomicalfeatures of the patient's anatomy using the registration of pin 3012 tothe anatomical features of the patient's anatomy. Guiding element 3000can therefore be expressed in the same frame of reference as anatomicalfeatures of the patient's anatomy and therefore the same frame ofreference as the surgical plan. The desired configuration of guidingelement 3000, that is to say the desired position of tool guide 3004, orin this embodiment the desired settings for the ratcheted pivot andmutually twistable components in order to enable a surgical interactionwith a patient in accordance with the surgical plan can thereby bedetermined.

The software outputs the desired configuration following the anatomicalregistration of the impression element and carrier 14′ that has allowedthe placement of a pin(s) into known locations on patient anatomy. Thesoftware will know the locations of these pins thus can output thecorrect configuration of the tool 3000 such that it can be modified bysurgical staff and placed over the pins in a known way. The toolguidance element 3004 can now be drilled through, entering the patientanatomy in a known way according to the surgical plan.

In some embodiments, a programmable tool can be registered to patientanatomy exclusively using an impression element without a carrier. Adigital or surgical plan is created based on patient imaging data. Intheatre, the surgical site is exposed and the surgeon can place aguidance pin or screw at a location of their choosing such as pin 3012depicted in FIG. 20 that possesses a known orientating factor such asflange 3014. Alternatively, the surgeon can use a separate tool to placetwo parallel pins in such a configuration that the standard part ofprogrammable tool 3010 can be slid over the top thus ensuring a knownplanar orientation.

These pins can be registered with patient anatomy so that a programmabletool can be appropriately modified and affixed to the pins such that itstool guidance feature 3004 is correctly positioned according to thesurgical plan.

Once the pin(s) are placed, a globular portion of sterile moldablematerial can be molded onto the surgical site ensuring that the pinspass through the globular body of material as it sets. When solidified,the globular body can be separated from the surgical site and slid offthe pins retaining a surface impression of the surgical site studdedwith the holes left by the pins that can or cannot pass all the waythrough the globular body.

Once remote from the surgical site, fresh sterile pins, or markers inthe same shape as the pins in the surgical site, can now be placed backinto the holes in the globular body such that they protrude out from thesurface possessing the impression from the surgical site. Thisarrangement can now be held in front of, for example, a 3D opticalscanner and scanned creating a 3D surface model. This 3D model willcomprise the impression of the surgical site and the pins or markersextending from the impression surface. In computer software, a surgeoncan now select the pin(s) or marker(s) on the computer model so that thesoftware can differentiate between the impression surface and themarkers. The software can now use the impression element surface andcarry out an anatomical registration in the above way. The axis andposition of the pin(s) marker(s) are inherently registered with theimpression element as they are in the same 3D scan thus once theimpression element is registered to patient anatomy in the normal way,the axis and position of the pin(s) marker(s) can also be expressed inthe same reference frame as the patient anatomy. In this way, thephysical pin(s) and marker(s) are now registered with respect to patientanatomy. As described previously, the computer software can nowcalculate an appropriate configuration or modification to be made to aprogrammable tool such that it can be slid over the original pin(s) insitu in the surgical site and used to carry out a surgical interventionon the patient.

A surgical pin can be designed with a specifically patterned head thatcan leave an impression in the impression element. In this embodiment,the scanner would scan the impression element producing a modelcomprising the surgical site impression as well as the impression of thepatterned head of the pin. This pattern can be picked up by software andused to register the location of the pin with respect to the impressionelement surface and subsequently to the patient anatomy. A programmableobject can be attached to the head of this pin in a known way thus,after appropriate modification, it can be used to guide a tool in theabove way.

Utility in Surgical Navigation

The herein described guide is solely limited to the guidance of surgicaltools. Surgical navigation has utility in a number of different surgicalfields and yet the majority of prior art functions with registrationtechniques that rely on optical registration methods or require thesurgeon to touch pre-determined areas of anatomy with a digitizer arm.These methods are laborious and time consuming and often require complexand costly equipment. In many situations this approach is impractical,for example, in compact operative fields where soft tissue can obscurethe view and the necessary bulky apparatus can be cumbersome andincrease the operation time.

The above described elements can be used to overcome these problems. Aguide can be provided with the intended function of orienting a‘standard marker’ that will be drilled into the patient's bony anatomy.This marker can be registered with the pre-operative imaging data andpatients anatomy utilizing the method disclosed above. The guide can beremoved from the surgical site and discarded leaving behind a ‘standardmarker’ fixed to the bony anatomy. The usual navigation techniques cannow be employed such as optical tracking of the ‘standard marker’ thusallowing conventional navigation techniques to be used. The advantage tothis approach is that the optical system can now be focused onto thefixed marker which can be away from the surgical site.

In some embodiments in which an impression element is modified by amodification tool, as well as defining the orientation and axialposition of a guide wire, pin or similar orthopaedic hardware, the guidecan be modified such that a depth to drill can be defined. This can beexplained in the following embodiment with respect to the TSA. A surgeonwill not want to penetrate the anterior wall of the scapulae whiledrilling a guide wire into the glenoid cavity. While the aforementionedprocesses are capable of guiding the axial position and orientation ofthe wire placement, it cannot define the depth the wire is placed intothe glenoid. This problem can be overcome with the use of a steppedhole. First, a wire guidance hole will be drilled through the guideblank. A second drill bit will now be employed of a greater diameter.This will drill along the same axis and in the same position as thefirst hole however it will not travel the full length of the guideblank. This process will produce a stepped shoulder within the originalguide hole. Once the guide is placed back into the surgical field, thesurgeon can now drill through the guide with a suitable guide wirefeaturing a corresponding ‘step’ in its design to correspond with theinternal ‘step’ within the guide hole through the guide. In planning theposition of the ‘step’, the microprocessor of the production apparatusis pre-programmed with information regarding the location of the ‘step’on the shaft of the drill bit used by the surgeon. With thisinformation, it can calculate the depth to drill the greater diameterhole through the guide blank to thus define the depth the guide wire canbe placed as the surgeon will be prevented, or at least deterred, fromdrilling further than the stepped shoulder allows. Alternatively, theprocessor can specify the position on the shaft of the guide wire toplace a lockable cuff in order to specify a specific depth. Thisposition is calculable due to the generated geometric knowledge of theimpression element of the guide blank with respect to the carrier andthe required depth to be drilled as defined in the surgicalprescription.

In some embodiments, a guide blank can be provided possessing certainmodifications to the carrier in the form of fixed members or markers,which can be considered to be fiducial markers extending out such thatwhen the impression element surface is viewed by a 3D scanner, the fixedmembers of the carrier are also visible in the scan. As a result ofthis, the scanning process generates a digital 3D model of theimpression element surface (as described above). This model can alsopossess 3D geometric data of the fixed members. The members areinherently geometrically fixed with respect to the carrier thus when theimpression element is scanned in the same reference frame as thesemembers, the impression element can be spatially registered with respectto the carrier. The device processor is programmed to create a virtualmodel of the position of the impression element with respect to thecarrier by registering the fixed members of a ‘blank’ model of a carrierwith the 3D image of the members from the scanned guide blank.

This embodiment allows for the 3D scanning components and the, forexample CNC, modification components of the aforementioned productionapparatus to be split into separate assemblies. For example, an operatorcan now take a mold of the joint surface in the described manner with aguide blank including fiducial markers. Once hardened, the guide blankis removed from the joint surface and held, possibly simply in thesurgeon's hand, with the molded impression element facing a 3D scannerthat might be held by a non-sterile assistant or positioned on a standon a separate table. The guide blank is optically 3D scanned producing a3D digital model comprising the molded impression element surface andthe optically visible fixed members extending from the carrier. This 3Dmodel is sent to a processor where the surface of the impression elementcan be registered with patient anatomy and hence the operativeprescription in the same manner as described in other embodiments. Theprocessor also registers the molded impression element surface withrespect to the carrier due to the presence of the members in the 3Dmodel generated by the 3D scanner. Once registration is complete, theguide blank can now be clipped into the guide blank receptor assembly ofa production apparatus consisting solely of the receptor assembly and amodification tool, such as a CNC drill, cutter or marker such as theconfigurations described above. In a similar manner to that describedabove, as a result of the fixed geometry of the carrier, it is onlypossible to affix the guide blank into the production apparatus in aknown position. The contours of the impression element are spatiallyregistered with the carrier therefore they are also inherently spatiallyregistered with the modification tool in the production apparatusthrough the standardized, carrier mediated fixation method. As a result,the modification tool can drill, cut or mark the guide blank in such away that when a tool is subsequently passed through the resultingguidance channels its path satisfies the constraints of thepre-operative prescription.

In other words, as described above, the guide blank does not necessarilyhave to have a carrier. The scanner, or rather the control unit, ‘knows’the location of items within the production apparatus so that if amolded lump of impression material is solidly fixed into the productionapparatus, the scanner can scan the molded section and inherentlyregister it to other items within the production apparatus so that itcan be appropriately modified.

In addition, by providing a fiducial marker on the carrier that isscanned along with the impression element, it is not necessary to havethe scanner and modification tool in the same apparatus.

In some embodiments, instead of a modification tool, a modificationguide is provided in the production apparatus. This works insubstantially the same way as the modification tool, except that it issimply positioned in a desired location with respect to the guide blankto guide a separate external tool to modify the guide blank in thedesired manner.

It is possible to use a surface configuration recorder to producesurface data representing a surface configuration. In the embodimentsabove, the surface data is obtained using a scanner. However, in someembodiments, it is possible to use a digitizer arm which can be touchedon a plurality of points on the impression element surface.

All optional and preferred features and modifications of the describedembodiments and dependent claims are usable in the various taughtherein. Furthermore, the individual features of the dependent claims, aswell as all optional and preferred features and modifications of thedescribed embodiments are combinable and interchangeable with oneanother.

Embodiments can be provided in accordance with the following clauses:

A method for the intraoperative production of a surgical guide, jig ornavigation tool utilizing pre-operative imaging data.

An apparatus for the intraoperative modification of a jig to a plannedgeometry such that it can be fitted to the patient and used to guidecutting/drilling intra-operatively

An apparatus for the local intraoperative modification of a jig that hasbeen fitted to a patient intra-operatively, modification to take placeaccording to 3D digital planning data

An apparatus for the local intraoperative modification of a jig that hasbeen fitted to a patient intra-operatively, modification to take placeaccording to 3D digital planning data, said apparatus incorporating awork chamber wherein the modification of the jig takes place, saidchamber can be dressed with sterile protective sheets, enclosures orbespoke lining materials such that the process of adaptation can takeplace in a sterile micro-environment.

A CNC or other variety of digital/programmable cutting or drillingapparatus for the local intraoperative modification of a jig that hasbeen fitted to the patient intra-operatively, modification to take placeaccording to 3D digital planning data, as described in previous clauses.

An apparatus for the intraoperative modification of a jig that has beenfitted to the patient intra-operatively, modification to take placeaccording to digital 3D planning data, following co registration ofpreoperatively acquired digital data with 3D data obtained at the timeof operation.

A jig for use with the apparatus described in previous clauses, wherethe jig incorporates a prefabricated element that provides a frame ofreference for digital planning and modification, and permits fixation tosaid apparatus.

A jig which is in part formed from a moldable material, e.g. a siliconeimpression material or a thermoplastic material, which is used to formthe tissue fitting surface of the jig together with a rigid,standardized tray to carry said material.

An apparatus equipped with, or associated with a scanner capable ofscanning the moldable element of the jig to acquire 3D data to allowregistration of the jig with preoperative scan data.

A jig for use in computer assisted orthopaedic surgery, where said jigis assembled from a moldable material, e.g. a silicone impressionmaterial which is used to form the tissue fitting surface of the jig anda rigid tray to carry said material, wherein the tray itself provides aframe of reference for digital planning, and modification.

A jig which is assembled from a moldable material, e.g. a siliconeimpression material which is used to form the tissue fitting surface ofthe jig and a rigid tray to carry said material, wherein the tray itselfprovides a frame of reference for digital planning and modification,also incorporating elements that facilitate connection to an apparatuscapable of modifying the jig according to digital planning data

A device as in previous clauses where a jig is assembled from a moldablematerial, e.g. a silicone impression material which is used to form thetissue fitting surface of the jig and a rigid tray to carry saidmaterial, wherein the tray itself provides a frame of reference fordigital planning, and modification, and incorporates elements thatfacilitate connection to an apparatus capable of rapidly modifying thejig in a localized sterile enclosure, according to digital planning data

A method for the co-registration of patient surgical anatomy withpre-operative or intraoperative imaging data, where one dataset isacquired from that of the 3D surface of a moldable material,intraoperatively molded to the topography of exposed patient anatomy.

A jig with both a temporarily modifiable component and a standardizedcomponent, such that it can be located into position by the use of animpression material, used to take an impression of anatomy, which hasbeen directly surgically exposed in the course of an operation.

A jig according to previous clauses, which once an impression has beentaken of the relevant exposed anatomy, can be scanned and used to permitthe co-registration of the exposed surgical anatomy to previously orintraoperatively acquired image data (e.g. CT or MRI).

A jig as described in the previous clause which is able to be returnedinto the same position from where the impression was first taken once,having been rapidly and appropriately modified by an associatedapparatus to create cutting or drilling paths or channels.

A jig according to all previous clauses where physical fixation meanscan be provided at the time of molding of the registration device, toensure, or at least increase the likelihood of, the secure placement ofthe tool once it is returned to the position in which the mold wastaken.

A registration tool according to previous clauses with provision tointeract with an associated apparatus and be accordingly modified toproduce a surgical guide, jig or navigation aid.

A registration tool according to previous clauses capable of physicalmodification by means of a CNC process to produce a surgical drilling orcutting guide, jig, template or navigation aid.

An apparatus associated with the jig or registration tool described inprevious clauses capable of carrying out the computer controlledmodification of said customizable registration tool or jig.

A method and associated apparatus for the intraoperative fabrication ofa surgical drilling, cutting, or positioning guide which uses a computercontrolled apparatus to modify a registration tool composed of astandard component and a moldable part, modified according to aspecification generated by associated software

An apparatus as described in previous clauses used in combination withthe jig or registration tool described in previous clauses.

An apparatus for the creation of surgical cutting or drilling guides,which combines a scanner and CNC mill or drill, such that an object canbe modified to a surgical prescription for use as a surgical jig orcutting guide.

An apparatus for the creation of surgical cutting or drilling guides,which combines a scanner and CNC mill or drill, such that an object canbe modified to a surgical prescription for use as a surgical jig orcutting guide within a sterile drilling chamber.

A method for the intra-operative production of a cutting or drillingguide or jig substantially as described within the accompanyingdescription, figures, and clauses

A combination cutting or drilling guide and registration devicesubstantially as described in the accompanying description, figures, andclauses.

An apparatus for the modification of a registration device/jigsubstantially as described in the description, figures and clauses.

While particular elements, embodiments and applications of the presentinvention have been shown and described, it will be understood, that theinvention is not limited thereto since modifications can be made withoutdeparting from the scope of the present disclosure, particularly in thelight of the foregoing teachings.

What is claimed is:
 1. A method of producing a modification plan forproducing a surgical guide comprising: (a) obtaining a surface datumrepresenting a configuration of a surface of an impression elementproviding an impression of a surgical site; (b) obtaining an image datumof a patient's anatomy; (c) obtaining surgical plan datum providing asurgical plan with respect to features in said image datum representingan anatomical feature of said patient's anatomy; (d) registering saidimpression element using said surface datum and said image data withsaid anatomical features of said patient's anatomy; (e) producing saidmodification plan from said surgical plan datum using the registrationof said impression element with said anatomical feature, wherein saidmodification plan includes modifying said impression element forproducing said surgical guide.
 2. The method of claim 1, wherein saidimpression element is a molded element formed by being placed againstsaid surgical site.
 3. The method of claim 1, wherein said modificationplan includes instructions for operating a production apparatus tomodify said impression element.
 4. The method of claim 3 furtherincluding: (f) registering said impression element with said productionapparatus, wherein said production apparatus includes a modificationtool for modifying the impression element, wherein an instruction isbased on a calibrated position of said modification tool and saidregistration of said impression element with said production apparatus.5. The method of producing a surgical guide comprising: (a) a method ofproducing a modification plan for producing said surgical guide, whereinsaid method of producing a modification plan comprises: (i) obtaining asurface datum representing a configuration of a surface of an impressionelement providing an impression of a surgical site, wherein said surfacedatum is obtained via a surface configuration recorder; (ii) obtainingan image datum of a patient's anatomy; (iii) obtaining surgical plandatum providing a surgical plan with respect to features in said imagedatum representing an anatomical feature of said patient's anatomy; (iv)registering said impression element using said surface datum and saidimage data with said anatomical features of said patient's anatomy; and(v) producing said modification plan from said surgical plan datum usingthe registration of said impression element with said anatomicalfeature, wherein said modification plan is a plan for modifying saidimpression element for producing said surgical guide; (b) modifying saidimpression element in accordance with said modification plan.
 6. Themethod of producing a surgical guide according to claim 5, whereinmodifying said impression element in accordance with said modificationplan includes operating a production apparatus to modify said impressionelement in accordance with said modification plan to produce saidsurgical guide.
 7. The method of producing a surgical guide according toclaim 5 further comprising: (c) placing a moldable element against saidsurgical site to form said impression element.
 8. A production apparatusfor the production of a surgical guide, including: (a) a receptorassembly for receiving an impression element conforming to a shape of asurgical site; (b) a surface configuration recorder for recording aconfiguration of a surface of said impression element to produce asurface datum for registering said impression element with an anatomicalfeature of a patient's anatomy and with said production apparatus; (c) aprocessor configured to determine patient registration data from imagedata of a patient's anatomy and said surface datum, wherein aregistration datum of said patient provides a registration of saidimpression element with said anatomical feature; and (d) a modificationtool for modifying said impression element, wherein said modificationtool and said impression element are positionable in a plurality ofpredetermined relative positions to allow said impression element to bemodified in accordance with a modification plan, wherein saidmodification plan is a plan for modifying said impression element and isderived from a surgical plan and a registration of said impressionelement with said anatomical feature of said patient's anatomy.
 9. Theapparatus of claim 8, wherein said modification tool includes a toolselected from the group consisting of a cutter for cutting saidimpression element, a drill for drilling said impression element, amilling component for milling said impression element, a slot saw forsawing, and a marker for marking said impression element.
 10. Theapparatus of claim 8 further comprising: (e) a processor fordetermining, from said modification plan and a registration of saidapparatus with said impression element, a desired relative position ofsaid modification tool with respect to said impression element to enablesaid impression element to be modified in accordance with saidmodification plan.
 11. The apparatus of claim 8, wherein said processoris configured to obtain said modification plan from an externalcomputing device.
 12. The apparatus of claim 8, wherein said processoris configured to determine how to modify said impression element inaccordance with said surgical plan by using said registration data todetermine how a respective impression element will align with saidsurgical site, and thereby determining how to modify said impressionelement in order to provide a configuration at said surgical site thatis in accordance with said surgical plan.
 13. The apparatus of claim 8,wherein said processor is configured to register said impression elementwith said production apparatus, using said surface datum.
 14. Theapparatus of claim 8, wherein a processor is configured to be calibratedwith a relative position of said surface configuration recorder and saidmodification tool.
 15. The apparatus of claim 8, wherein a control unitis configured to adjust a position of said receptor assembly and saidmodification tool to enable modification in accordance with saidmodification plan.
 16. The apparatus of claim 8, wherein a control unitis configured to control said modification tool to modify saidimpression element in accordance with said modification plan.
 17. Theapparatus of claim 8, wherein a control unit is calibrated with relativepositions of said surface configuration recorder and of saidmodification tool.
 18. The apparatus of claim 8, wherein said controlunit is configured to obtain a spatial registration datum providing aregistration of said impression element with said apparatus, and whereinsaid control unit is configured to control the modification tool tomodify a received impression element in accordance with a modificationplan using said spatial registration datum.
 19. The apparatus accordingto claim 8, wherein said apparatus is part of a kit for producing saidsurgical guide, wherein said kit also comprises a moldable material forplacing against said surgical site to form said impression element. 20.A computer program for performing said method of claim 1 when executedon a computing device.